SH/T 0074-1991 Determination of thin-layer oxygen absorption oxidation stability of gasoline engine oils

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Card type: Test method

1. Method number / full title / English name / replacement relationship

• Standard number: SH/T 0074-91
• Chinese full title: Determination of thin-layer oxygen absorption oxidation stability of gasoline engine oils
• English name: not provided in the available source (the main text only mentions reference to and adoption of ASTM D4742-88 "Determination of thin-layer oxygen absorption oxidation stability of gasoline engine oils TFOUT")
• Replacement relationship: not provided in the available source
• Approval/implementation: approved by China Petrochemical Corporation 1991-06-28, implemented on 1992-07-01
• Technical committee: technically administered by the Research Institute of Petroleum Processing
• Drafting organization: Refinery of Beijing Yanshan Petrochemical Company
• Main drafters: Yu Guohui, Yu Tiezhu

2. Applicable scope and non-applicability

• This standard specifies the determination of the oxidation stability of gasoline engine oils by a high-temperature thin-layer oxygen absorption simulation evaluation method.
• It is applicable to evaluating the oxidation stability of gasoline engine oils with a viscosity (100℃) range of 4～21 mm²/s under high-temperature conditions.
• It can be used as a screening test for the MS Procedure ⅢD method.
• Not applicable: not provided in the available source.

3. Method principle

Mix the test oil, two catalysts and distilled water in a glass sample container, and place it in an oxygen bomb equipped with a pressure gauge. At room temperature, charge the oxygen bomb with 620 kPa (90 psig) oxygen, place it in an oil bath at 160℃, at 30° to the horizontal, and rotate it axially at a speed of 100 r/min. A thin film of oil is formed in the sample container, allowing effective contact between the oil and oxygen. When the test reaches the specified pressure drop, record the time. Evaluate the high-temperature oxidation stability of gasoline engine oils based on the test time.

4. Reagents and materials (purity / preparation)

4.1 Reagents

• 4.1.1 95% ethanol: chemically pure.
• 4.1.2 acetone: chemically pure.
• 4.1.3 potassium hydroxide: analytically pure.
• 4.1.4 petroleum ether: 60～90℃, analytically pure.
• Note: ethanol and petroleum ether are flammable. Acetone is flammable and irritates the skin, and inhalation is harmful. Potassium hydroxide is corrosive.

4.2 Materials

• 4.2.1 Fuel component catalyst: use the standard reference material (SRM 1817) see the fuel component catalyst in Annex A1, and its preparation is given in Annex A2.
• 4.2.2 Soluble metal catalyst: use the soluble metal catalyst in SRM 1817, and its preparation is given in Annex A3.
• 4.2.3 Distilled water for testing: use the distilled water in SRM 1817.
• 4.2.4 Oxygen: purity not less than 99.5%. Note: high-speed jets are easily combustible; keep away from oil and grease.
• 4.2.5 Kerosene for lamps: meets the requirements of GB 253.
• 4.2.6 Solvent naphtha: meets the requirements of grade 120 or grade 200 in GB 1922.
• 4.2.7 High-temperature sealing silicone grease.
• 4.2.8 Fine yarn gloves.
• Note: the fuel component catalyst is flammable, inhalation of its vapor is harmful, and repeated contact irritates the skin. The soluble metal catalyst is flammable, toxic, and harmful if inhaled. Operations with both catalysts should be carried out in a ventilated environment.

6.1 1% Preparation of potassium hydroxide ethanol solution

Dissolve 12 g potassium hydroxide in 95% ethanol. (The original text states "dissolve 12g potassium hydroxide in ethanol compared with 95%", which is suspected to be source-text extraction noise and requires confirmation against the source standard (source-text extraction); the amount of ethanol is not provided in the available source.)

5. Apparatus and equipment

• 5.1 Oxygen bomb, pressure gauge and test oil bath: meet ZB E 34011; the oxygen bomb assembly is shown in Figure 1.
• 5.2 Glass sample container: made of borosilicate glass, dimensions are shown in Figure 2.
• 5.3 Filler aluminum ingot: dimensions are shown in Figure 3; surface roughness: the roughness symbol is illegible in the source transcription and remains unverified; material: ZL 1030 (the original text is "ZL 1 030", requires confirmation against the source standard (source-text extraction)).
• 5.4 Thermometer: mercury thermometer, 150～200℃, with a scale division of 0.1℃ (the original text is "0.1ccI", requires confirmation against the source standard (source-text extraction)).
• 5.5 Pan-type torsion balance: maximum weighing capacity 100 g, sensitivity 0.01 g.
• 5.6 Microsyringe: 50, 100 μL, with a scale division of 0.2 μL (the original text is "50, 1001A, with a scale division of 0.2KLo", requires confirmation against the source standard (source-text extraction)).
• Figure 1 Oxygen bomb assembly drawing: 1— bomb handle; 2— flat cover; 3— locking ring; 4— "O"-shaped sealing ring; 5— polytetrafluoroethylene cover; 6— sample container; 7— filler aluminum ingot; 8— bomb body.
• Figure 2 Glass sample container.
• Figure 3 Filler aluminum ingot.

6. Recommended operating conditions

• Oxygen bomb charging pressure: at room temperature 620 kPa (90 psig).
• If room temperature is not 21℃, then for every increase (or decrease) of 1℃, adjust the pressure higher (or lower) by 2.5 kPa (0.4 psig).
• Oil bath temperature: 160℃.
• Test temperature maintenance: 160℃±0.1℃.
• Oxygen bomb placement angle: 30° to the horizontal.
• Rotation speed: 100 r/min±5 r/min.
• The oil bath should return to the test temperature within 15 min after the oxygen bomb is inserted (the bath temperature-recovery time is garbled in the source transcription and remains unverified).
• Test termination pressure drop: a decrease of 172 kPa from the highest point (25 psig).

7. Sampling and sample preparation

• 7.1 Wear clean fine yarn gloves, and weigh 1.50 g±0.01 g of sample in the glass sample container.
• 7.2 Take out the test catalyst from SRM 1817, and shake thoroughly before drawing. In a ventilated environment, inject into the test material respectively fuel component catalyst 80 μL, soluble metal catalyst 70 μL, and water 30 μL. Gently rotate the sample container to mix the test material and catalysts uniformly. Use a 100 μL syringe for the fuel catalyst and metal catalyst, and use a 50 μL syringe for water (the original text is "10OKL" "S04", requires confirmation against the source standard (source-text extraction)).
• Note: Once the catalyst bottle is opened, it must be used immediately. The syringe used for adding the metal catalyst must be cleaned with a small amount of petroleum ether after use, then the needle handle removed and air-dried.

8. Analysis procedure

• 6.2 Rinse the glass sample container with petroleum ether, then wash it clean with soapy water and distilled water, finally rinse with acetone, and blow it dry with clean compressed air. Wash the oxygen bomb, filler aluminum ingot, polytetrafluoroethylene cover and "O"-shaped sealing ring with soapy water and distilled water, and air-dry them.
• 6.3 Draw and wash the interior of the oxygen bomb stem with 1% potassium hydroxide ethanol solution, then draw and wash it clean with 95% ethanol, and blow it dry with cold air.
• Note: If the sample container and oxygen bomb stem are not thoroughly cleaned, it will adversely affect the test results.
• 6.4 Raise the temperature of the test oil bath to 160℃.
• 7.3 Assemble the oxygen bomb according to Figure 1. Slide the aluminum ingot into the oxygen bomb, then place in the sample container and cover with the polytetrafluoroethylene cover. Put the "O"-shaped sealing ring onto the flat cover, and apply a thin layer of sealing silicone grease on the outer layer. Then put on the flat cover of the oxygen bomb and tighten the locking ring by hand. Wind the instrument clock spring, install the recording paper, and fill in the oxygen bomb number, test number and test date.
• 7.4 Open the needle valve, slowly rinse twice with oxygen at a pressure of about 620 kPa (90 psig), and release to atmospheric pressure, then charge again and accurately adjust to 620 kPa (the original text is "21-", requires confirmation against the source standard (source-text extraction)), and close the valve tightly. If room temperature is not 21℃, then for every increase (or decrease) of 1℃, adjust the pressure higher (or lower) by 2.5 kPa (0.4 psig). If necessary, immerse the bomb body in water or use soapy water to check for leaks. The oxygen bomb used for leak testing must be wiped dry with a dry towel and dried with compressed air or a hair dryer.
• Note: The oxygen bomb pressure gauge should be calibrated regularly. The reading error of the pressure gauge should not be greater than 2%.
• 7.5 After the oil bath reaches the test temperature, turn off the rotating rack. Insert the prepared oxygen bomb into the rotating rack, record the time, and then start the rotating rack. The oil bath should return to the test temperature within 15 min after the oxygen bomb is inserted. Maintain the test temperature at 160℃±0.1℃.
• 7.6 Throughout the entire test, the oxygen bomb must be completely immersed and rotate continuously and uniformly. The required rotation speed is 100 r/min±5 r/min.
• 7.7 When the test pressure drops by 172 kPa (25 psig) from the highest point, turn off the rotating rack, record the time, and remove the recording paper. Immediately take out the oxygen bomb, and while hot place it in a cleaning tank of kerosene for lamps and solvent naphtha for cleaning, then rinse with tap water to cool.
• 7.8 Open the needle valve and release the residual gas. Open the oxygen bomb and take out the polytetrafluoroethylene cover and glass sample container. Remove the "O"-shaped sealing ring from the flat cover. Clean the oxygen bomb body, flat cover and locking ring with solvent naphtha, then wash clean with soapy water and distilled water and air-dry. Repeat the cleaning process of clauses 6.2 and 6.3.

9. Qualitative and quantitative determination and calculation formula

• 8.1 Calculation of oxidation induction period time: the time from the start of the oxygen bomb test until the pressure drops by 172 kPa (25 psig) from the highest point, calculated in minutes (min).
• 8.2 Take the arithmetic mean of two results as the test result of the sample oxidation stability, expressed in minutes (min).
• Calculation formula: not provided in the available source (only expressed as time, no calculation formula).

10. Precision

Use the following provisions to judge the reliability of the results (95% confidence level).

• 9.1 Repeatability: For twenty consecutive determinations by one operator using the same instrument and the same test materials, operating normally and accurately according to the test method, and with the instrument running stably, only one result is allowed to exceed the following value:
  • 0.10 (X+5 min)……(1)
  • X— The average value of repeated determination results expressed in minutes (min).
• 9.2 Reproducibility: For twenty test results determined by different operators in different laboratories using the same test material according to normal and accurate test methods, only one is allowed to exceed the following value:
  • 0.22 (X+5 min) ... (2)
  • X— is the average of the results obtained by two laboratories, expressed in minutes (min).

11. Report

• 8.1 The oxidation induction time is calculated as the time from the start of the test in the oxygen bomb until the pressure drops from its highest point by 172 kPa (25 psig), calculated in minutes (min).
• 8.2 Take the arithmetic mean of two results as the test result for the oxidation stability of the sample, expressed in minutes (min).

12. Referenced Documents

• GB 253 Kerosene for lamps
• GB 1922 Solvent naphtha
• GB 7304 Determination method for neutralization value of petroleum products and lubricants (potentiometric titration method)
• ZB E 34011 Determination method for oxidation stability of lubricating oils (rotating oxygen bomb method)
• Reference adoption: ASTM D4742-88 "Determination method for thin-layer oxygen absorption oxidation stability of gasoline engine oils TFOUT"

Editor's note: The standard numbers and standard names of the referenced standards in this standard have changed as follows:

13. Source and verification

This page is an AI translation of the available Chinese method card. Human verification is pending. It is not an official translation of the standard. Check the source standard and product certificate before use.

14. Quick Reference Q&A